How to convert rotation_axis_angle to euler or quaternion via Python?
Via mathutils.Matrix.Rotation constructor.
Given an axis angle rotation provides just that, can make a matrix from the components.
Matrix.Rotation(angle, size, axis)
&gt;&gt;&gt; q
Quaternion((0.44383183121681213, -0.3263395428657532, 0.8345092535018921, 0.010497181676328182))
&gt;&gt;&gt; axis, angle = q.to_axis_angle()
&gt;&gt;&gt; R = Matrix.Rotation(angle, 4, axis) # or size 3
&gt;&gt;&gt; R.to_quaternion()
Quaternion((0.44383174180984497, -0.3263395428657532, 0.8345093727111816, 0.010497150011360645))